Raman spectroscopy on the identification of the organic mordant used in gilding decoration of Persian archaeological tiles

Abstract

Several organic reference materials including gums, proteins and oils, as well as the organic mordant used for adhering gold leaf on ten archaeological Persian gilded tiles dated from the fourteenth to the sixteenth century were studied by Raman spectroscopy. The relative surface area under the spectral components of the C–H stretching region from the reference materials and archaeological samples were used as criteria for identifying the class of the organic material used as mordant. Our studies showed that a drying oil has most probably been used as mordant in the archaeological samples. Also, the possibility of the use of gum ammoniac as gilding mordant is considered.

Notes

Acknowledgements

We are grateful to Majid Olumi for providing the gilded tiles from Yazd, and Hamed Sayyadshahri for providing the gilded tiles from Takht-i Sulayman and Madrasa-i Ghiyathiyya. We are indebted to Hushang Jazizadeh and Mahmud Lahijaniyan for supplying the reference binding mediums. Carmela Vaccaro from the University of Ferrara, Italy, is cordially thanked for providing the μ-Raman facility.

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Supplementary material

ESM 1Deconvoluted Raman spectra of some reference materials and archaeological gilding mordants in the C–H stretching region and summary of information on the glazed tiles and their gilding mordant (PDF 750 kb)